The invention relates to a method of fulfilling orders in a warehouse with an order fulfillment area.
When operating a warehouse with an order fulfillment area several aspects must be taken into account as described below.
While picking or compiling orders from transporting units, such as e.g. articles or containers, it is necessary to provide the transporting or storage units, which are associated with a common order, in a directed or sorted fashion. In addition, it is conventional to intermediately store (buffer) the transporting units of an order, until all of the transporting units required for the order are present. They are then passed together onto a collecting line which leads them e.g. to the palletization area, picking station, goods issue, shipment etc.
At the picking station the goods for fulfilling an order are taken from the storage units (receptacles) and placed according to the order into an order container etc. The storage unit (often called donor) is then routed back into the racking storage and stored until needed for the next order.
Order fulfillment of orders placed over the Internet must take place within a relatively short period of time in order to be commercially competitive. Such order fulfillment is known as E-commerce and places demands on an order fulfillment system to meet such obligations. This is compounded by the fact that E-commerce usually involves a large number of small orders (each containing as few as one item in the order) that are selected from a large number of potential items. Each unique item has a specific inventory identification, known in the industry as a stock-keeping unit (SKU). Each item usually bears an optical code, such as a barcode or radio frequency identification (RFID) tag that identifies the SKU of the item.
Because of the large number of SKU's from which an order may be selected, the inventory warehouse may be very large in footprint. As such, it is common to designate geographic portions of the inventory warehouse to each be picked by an individual picker such that each picker picks only a portion of each order, since each order may be spread out over the entire general footprint of the inventory warehouse. Each picker is directed by a warehouse management system to pick portions of a number of orders using a various picking technology known in the art. It is efficient to have the picker mix several orders in one picking or picked receptacle rather than having multiple receptacles, each bearing one order portion. In this way, each order may be contained in a number of picked receptacles if the order contains more than an individual item. However, it is then necessary to subsequently sort the contents of the picked receptacle(s) to the order and to process the items so that they can be packed-out for shipment via courier. Also, orders may be made up of items having various physical characteristics such that some items are not able to be readily handled by a conventional material-handling system. Such items are known as non-conveyables.
EP 1 590 272 B1 discloses use of mobile inventory pods in the form of autonomous robotic mobile trays that store and transport inventory items based on instructions from a central computer.
EP 2 170 742 B2 discloses a method in which at a singulation station of a materials handling facility, individual units of items from collections of items are selected, wherein the collection of items includes units of heterogeneous items picked from inventory storage of the materials handling facility to fulfill a plurality of orders; associating an item identifier of a particular item of the individual units of items with a receptacle identifier of a particular conveyance receptacle of a plurality of conveyance receptacles; associating the particular conveyance receptacle with a particular order that specifies at least one unit of the particular item. In Other words articles from a mixed or dirty batch picking process are singulated by putting a single separate article into/onto a conveyance receptacle and marrying these by correlating their identifiers in a database. From then on only the receptacle identifier is tracked throughout the facility.
US 2011/0295413 A1 also discloses singulation of batch wise picked items from a batch container into single containers with a single item per container.
Further it is difficult to manage fluctuations in demand within storage facilities. Manually run storage facilities with manual pack stations usually capable of managing the fluctuation and have low initial costs and can be very effective for very slow moving articles in general and fast moving particularly across limited articles and low cost labor situations. However they must be larger in space to handle the same amount of orders as automated high bay systems. In addition, it is difficult to control the progress of manual operations in the timely fashion and running cost and even availability of labor may become an issue in high cost labor situations.
Slow-movers are items which are infrequently asked for in orders and therefore have longer storage duration. In contrast fast-moving items are items which are frequently used for order fulfillment and therefore have short storage duration.
Common procedure is to store both such slow-moving and fast-moving products within the same automated storage system. If the amount of so-called slow-moving products is high, it means that a lot of storage locations within the automated storage system are occupied with items that are rarely needed. If only so-called fast movers are stored in the automated storage system, it is necessary to provide a second storage. Both situations increase costs as storage locations have to be provided. Further, if slow moving products are stored within manual shelving, an operator needs to walk around and pick those products manually. Since those are slow movers, the operator has to spend a majority of his time walking to the location where products are stored rather than for the picking operation itself. Batch picking would be the most effective way to minimize the walking distance per pick but still a great amount of walking time is required and also the separation of the batch picked items is tiresome and causes require duplicate handling of the products, one for the batch pick and one for the separation from the batch pick.